Sharing files between XP and Win 7 on Homegroup

I linked computers just fine, Win 7 computer see's and allows sharing with XP system but XP system does see Win 7 machine but won't allow sharing of files even though it shows the folders are shared. Says I don't have permission to access folders. Do I need to be in Administrator mode to do this?

Thanks for the info Irv S., The computers are a friend of mine and She is away for awhile so I won't be able get back to it until next week. I'll keep you posted. By the way the two computers are on a Home Network and both in the same Homegroup. The Win 7 computer see's and will share the folders and files just fine. The problem is with the XP machine, but it also sees the Win 7 files and folders, just gives me an error about access due to permissions. I believe I have to go into the users and check the permissions there and than add them to the win 7 machine. I used to do this stuff all the time when working but I've gotten a little rusty. Thanks.
Ted